The standard library, that first line of code, it's not strictly necessary but any time you use a function, a tool that someone else wrote that lives in that so called library, you do need that include line as we'll see.

标准库函数--第一行代码，严格来说，不是每次都要写的，但是一旦你调用某个别人写，的函数，而这个函数又恰巧位于标准库里面,你就要像我们看到的这样，把它include进去。

哈佛公开课 - 计算机科学课程节选

So, certainly the CS50 Library designed to be dynamic and, in fact, any time you call get string, we are, in fact, ; allocating a chunk of RAM but it's not coming from the stack; it's actually coming from this portion of memory called the heap.

所以，Cs50库是动态设计的，实际上，每次你调用GetSting时，我们分配一块内存，但它不是来自栈;,而是来自于叫做堆的,内存的一部分。

哈佛公开课 - 计算机科学课程节选